<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>

    <button>获取验证码</button>

    <script>

        const oBtn = document.querySelector('button');

        oBtn.onclick = function () {
            this.innerHTML = '10s';
            this.disabled = true;
            let count = 10;
            // let t = setInterval(function () {
            //     count--;
            //     console.log(this);   // window
            //     oBtn.innerHTML = count + 's'
            // }, 1000)

            let t = setInterval(() => {
                count--;
                console.log(this);   // window
                this.innerHTML = count + 's'
            }, 1000)
        }

    </script>

</body>

</html>